Abstract:Viral infection of cells is a highly intricate process that involves the complex virus-cell interactions. Recently, virologists can monitor the virus life cycle at the primary infection site in real-time using various virus tracking techniques. Herpesviruses, a class of large enveloped DNA viruses, are important pathogens threatening the health of humans and animals. This review discussed the applications of different virus tracking techniques in herpesvirus studies, to provide new insights into virus-cell interactions and replication mechanisms of herpesviruses. Though the techniques have widely been exploited, some issues need to be addressed, such as the selection of the optimal site to insert reporters and the inability to track the whole process of the virus life cycle. With the updated tracking techniques, hopefully, more complex replication mechanisms of herpesviruses will be revealed in detail.

Abstract:Plant stem cells are the cells that are located in meristems and are kept in a state of undifferentiation. Plant stem cell possesses lower vacuolization, higher mitochondrial activity, more genetic stability and stronger self-renewal capacity compared with calli. Plant stem cell culture has a wide application in pharmaceutical, functional food as well as cosmetic industries. Here we describe the procedure of induction, isolation and identification of plant stem cells, to provide a reference for further research in this field.

Abstract:Lamin B1 is one of the essential members of the nuclear lamina protein family. Its main function is to maintain the integrity of nuclear skeleton, as well as to participate in the cell proliferation and aging by affecting the chromosome distribution. gene expression, and DNA damage repair. The abnormal expression of lamin B1 is related to certain diseases, including neurological diseases [e.g. neural tube defects (NDTs), adult-onset autosomal dominant leukodystrophy (ADLD)] and tumors (e.g. pancreatic cancer). It is also a potential tumor marker as well as drug target. Further research on lamin B1 will help people understand the molecular mechanism of the emergence and development of neural system diseases and tumors, and define a new future in drug target.

Abstract:To explore the activity of the pmel core promoter of Bashang long-tail chickens, we constructed dual-luciferase expression vectors and transiently transfected into DF1 cells with Lipofectamine 2000. We measured the luciferase activity with the dual-luciferase detection kit. The 1 268 bp fragment in 5￠-flanking region of the pmel gene in Bashang long-tail chickens was cloned. The region from ?1 200 bp to +68 bp included 2 CpG islands and multiple transcription factor binding sites. We constructed 9 expression vectors with different promoter regions and a mutant vector of the core promoter region of the pmel gene of Bashang long-tail chickens. The core promoter region from –840 bp to +68 bp was identified in the pmel gene. The region from ?590 to ?525 bp negatively regulated the pmel gene during the transcription process. The ?840—?590 bp and ?525—?266 bp regions were positive regulatory regions. The polymorphic sites (?456, ?435, ?410, ?374 and ?341) had a significant effect on the promoter activity of the pmel gene.

Abstract:Promoter, an essential regulatory element, is widely used for metabolic engineering of industrial strains. Corynebacterium glutamicum is an important industrial workhorse to produce various amino acids. However, strong constitutive promoters that are applicable to C. glutamicum are rarely reported. In this study, we first performed a time-series transcriptome analysis of a glutamate hyper-producing strain C. glutamicum SL4 by using RNA-Seq. Overall, we picked 10 samples at different time during the fermentation process. By analyzing the time-series transcriptome data, we selected 10 candidate genes with the highest transcriptional level. These genes were all transcribed stably during the fermentation process. We subsequently cloned the promoter sequences and evaluated the promoters’ strength in strain SL4 using a red fluorescent protein reporter system. To evaluate the universality of the promoters in different C. glutamicum strains, we further tested the performance of some promoters in wild type C. glutamicum strains, including ATCC 13869 and ATCC 13032. The strongest promoter was further characterized using LacZ as a reporter in all the three C. glutamicum strains. Finally, we successfully obtained three constitutive promoters with universality, PcysK, PgapA and PfumC. PcysK is the most efficient promoter among the three C. glutamicum strains. In strains SL4 and ATCC 13869, the strength of PcysK is 2-fold of the strong inducible promoter Ptac using the red fluorescent protein as a reporter and 4-fold of Ptac using LacZ as a reporter. Moreover, the strength of PcysK reaches 30%?40% of Ptac in strain ATCC 13032. The promoter PcysK is identified as a strong promoter for the first time, which can be used as an efficient biobrick for metabolic engineering of synthesis pathways in C. glutamicum.

Abstract:Glucaric acid (GA), a top value-added chemical from biomass, has been widely used for prevention and control of diseases and the production of polymer materials. In GA biosynthesis pathway, the conversion of inositol to glucuronic acid that catalyzed by myo-inositol oxygenase is the limiting step. It is necessary to improve MIOX activity. In the present study, we constructed a high-throughput screening system through combing the concentration of GA with the green fluorescent protein fluorescence intensity. By applying this screening system, three positive variants (K59V/R60A, R171S and D276A) were screened from the mutant library. In comparison, the recombinant strain Escherichia coli BL21(DE3)/MU-R171S accumulated more GA, 136.5% of that of the parent strain.

Abstract:Heparin is a very important anticoagulant drug. Currently, heparin is mainly extracted from porcine mucosa. However, animal-derived heparin shows low anticoagulant activity due to the low proportion of the anticoagulant active unit, the GlcNS6S-GlcA-GlcNS6S3S-Ido2S-GlcNS6S pentasaccharide. In this study we proposed an enzymatic strategy to sulfate the animal-sourced heparin to increase the proportion of anticoagulant pentasaccharide and the anticoagulant activity. First, three sulfotransferases HS2ST, HS6ST, and HS3ST were expressed tentatively in Escherichia coli and Pichia pastoris. After measuring the sulfotransferase activity, we confirmed P. pastoris GS115 is the better host for sulfotransferases production. Then, the maltose binding protein (MBP) and thioredoxin (TrxA) were fused separately to the N-terminal of sulfotransferases to increase enzyme solubility. As a result, the yields of HS2ST and HS6ST were increased to (839±14) U/L and (792±23) U/L, respectively. Subsequent sulfation of the animal-sourced heparin with the recombinant HS2ST, HS6ST and HS3ST increased the anticoagulant activity from (76±2) IU/mg to (189±17) IU/mg.

Abstract:In order to clarify dynamic change of microbial community composition and to identify key functional bacteria in the cellulose degradation consortium, we studied several aspects of the biodegradation of filter papers and rice straws by the microbial consortium, the change of substrate degradation, microbial biomass and pH of fermentation broth. We extracted total DNA of the microbial consortium in different degradation stages for high-throughput sequencing of amplicons of bacterial 16 S rRNA genes. Based on the decomposition characteristics test, we defined the 12th, 72nd and 168th hours after inoculation as the initial stage, peak stage and end stage of degradation, respectively. The microbial consortium was mainly composed of 1 phylum, 2 classes, 2 orders, 7 families and 11 genera. With cellulose degradation, bacteria in the consortium showed different growth trends. The relative abundance of Brevibacillus and Caloramator decreased gradually. The relative abundance of Clostridium, Bacillus, Geobacillus and Cohnella increased gradually. The relative abundance of Ureibacillus, Tissierella, Epulopiscium was the highest in peak stage. The relative abundance of Paenibacillus and Ruminococcus did not change obviously in each stage. Above-mentioned 11 main genera all belonged to Firmicutes, which are thermophilic, broad pH adaptable and cellulose or hemicellulose degradable. During cellulose degradation by the microbial consortium, aerobic bacteria were dominant functional bacteria in the initial stage. However, the relative abundance of anaerobic bacteria increased gradually in middle and end stage, and replaced aerobic bacteria to become main bacteria to degrade cellulose.

Abstract:Bacillus thuringiensis (Bt) produces Cry toxins that are widely used as insecticides in agriculture and forestry. Receptors are important to elucidate the mode of interaction with Cry toxins and toxicity in lepidopteran insects. Here, we purified the Cry toxin from Bt and identified this toxin by flight mass spectrometry as Cry1Ac, and then recombinantly expressed aminopeptidase N (BmAPN6) and repeat domains of cadherin-like protein (CaLP) of B. mori. Using co-immunoprecipitation (co-IP), Far-Western blotting, and enzyme-linked immunosorbent assays (ELISAs), we identified the interaction between Cry1Ac and BmAPN6. Furthermore, analysis of the cytotoxic activity of Cry1Ac toxin in Sf9 cells showed that BmAPN6 directly interacted with Cry1Ac toxin to induce morphological aberrations and cell lysis. We also used co-IP, Far-Western blotting and ELISAs to analyze the interactions of Cry1Ac with three binding sites corresponding to cadherin repeat (CR) 7 CR11, and CR12 of CaLP. Notably, the three repeat domains were essential Cry1Ac binding components in CaLP. These results indicated that BmAPN6 and CaLP served as a functional receptor involved in Bt Cry1Ac toxin pathogenicity. These findings represent an important advancement in our understanding of the mechanisms of Cry1Ac toxicity and provide promising candidate targets for gene editing to enhance resistance to pathogens and increase the economic value of B. mori.

Abstract:Leymus racemosus had a high resistant capacity to wheat scab (Fusarum head blight). The transfer of scab resistant gene from L. racemosus to Triticum aestivum is of great significance for broadening the germplasm of wheat resistance. To obtain Triticum aestivum–Leymus racemosus translocation line with scab resistance, we irradiated the pollen of T. aestivum-L. racemosus disomic addition line DA7Lr by 60Co-γ-rays 1 200 R (100 R/min) prior to pollinating to emasculation T. aestivum cv. Chinese Spring. One plant with one translocation chromosome was detected in the M1 by GISH. The plant with one translocation chromosome was self-pollinated, and at meiotic metaphase I its progenies with two translocation chromosomes were analyzed for chromosome pairing behavior in their pollen mother cells (PMCs). One rod bivalent was observed at meiotic metaphase I, indicating that the plant with two translocation chromosomes was one translocation homozygote. Sequential GISH-FISH analysis, using Oligo-pAs1-2 and Oligo-pSc119.2-2 as probe, translocation line was confirmed as T6DL·7LrS. The translocation line had higher resistance to wheat scab and feasibility to be used as a new source in wheat breeding resistant to scab disease.

Abstract:Epigenetic modification, especially histone modification, plays an important role in maintaining plant genome stability, regulating gene expression and promoting regeneration in vitro. MtSERK1 is an important marker gene involved in establishing of embryogenic callus during in vitro regeneration of Medicago truncatula. In order to understand the regulation relationship between dynamic histone modification and MtSERK1s expression during the processes of in vitro organogenesis, the expression of MtSERK1 was analyzed by qRT-PCR, and the modification status of H3K9me2, H3K4me3 and H3K9ac in the promoter region and different regions included in the gene body was analyzed by chromatin immunoprecipitation (ChIP). We found expression activation of MtSERK1 was related to the dynamic changes of histone H3K4me3 and H3K9ac in the 5′ and 3′ regions. This study will provide important theoretical guidance for understanding of the regulatory mechanism of MtSERK1 and also for establishing efficient genetic transformation system of Medicago truncatula.

Abstract:To explore the effect of high fat diet on proteome in mice stomachs, we constructed a model in which the mice were fed with high fat diet as the high fat diet (HFD) group or normal diet as the control (CTRL) group for 110 days. The stomachs were collected and divided into three regions (forestomach (F), corpus (C) and antrum (A)) for protein extraction and mass spectrometry analysis. Of all 9 307 identified proteins in two groups, 4 066 proteins (HFD: 3 832, CTRL: 3 654) were strictly identified by at least one unique peptide and identified twice in three replicates. Using gene ontology (GO) and interaction network analysis we analyzed differentially expressed proteins (fold change≥2) in two groups or between regions. In the whole stomach tissues, proteins up-regulated in HFD group mainly were associated with protein stabilization and protein transport. Differentially expressed proteins between regions showed that forestomach was related to the biological process of keratinization and actin assembly, while corpus and antrum mainly performed digestive function. Compared with forestomach, the corpus and antrum were more affected by the diet. Though there was no significant effect on the basic digestive function of the stomach, proteins that were involved in protein transport and lipid metabolism-related biological processes were significantly highly expressed in HFD group.

Abstract:The two-dimensional (2D) cell culture model is currently used to study cellular processes and drug screening for human diseases. However, the growth of cells is affected by many factors. For conventional 2D cell culture, many of the difficulties are encountered in accurately replicating the cell function in three-dimensional (3D) tissues. Compared with 2D cell culture, much attention is paid to the cell-to-cell and cell-matrix interactions for 3D cell culture systems, which can more closely mimic the growth environment for cultured cells. Therefore, the 3D cell culture system was more suitable for a variety of applications such as drug screening and cell proliferation. In this work, we prepared microarray-structured polymer films with different geometric structures by nanoimprint lithography and used the films as cell culture platforms for the culture of 293T cells. Through the adjustment of the surface morphology and water contact angle of the prepared films, the regulation of the morphological changes of cell growth was successfully realized. Experimental results demonstrated that the hydrophilic films with 10 μm-pillar microstructure are applicable to 3D cell culture, whereas the hydrophobic films with 3 μm-pillar microstructure are only suitable for 3D culture of cells with a smaller size and stiff cuticular layer. In addition, cells tended to the formation of spheroids on the hydrophobic films, while cells usually adhered to the surface and grew on the hydrophilic films. This work represents further technological progress in the development of 3D cell culture, thereby facilitating future studies of physiologically relevant processes.

Abstract:Small proteins (SPs) are defined as peptides of 100 amino acids or less encoded by short open reading frames (sORFs). SPs participate in a wide range of functions in cells, including gene regulating, cell signaling and metabolism. However, most annotated SPs in all living organisms are currently lacking expression evidence at the protein level and regarded as missing proteins (MPs). High efficient SPs identification is the prerequisite for their functional study and contribution to MPs searching. In this study, we identified 72 SPs and successfully validated 9 MPs from Saccharomyces cerevisiae based on SPs enrichment strategy. In-depth analysis showed that the missing factors of MPs were low molecular weight, low abundant, hydrophobicity, lower codon usage bias and unstable. The small protein-based enrichment can be used as MPs searching strategy, which might provide the foundation for their further function research.